How to be an external world realist?
I am a recovering solipsist who is now trying to embrace external world realism. I am seeking help from realists to help make me a better external world realist.
Observation 1: The world around me is completely saturated in color. So it seems like if I am going to be an external world realist then I must believe that colors are an objective property of the world around me. I must believe colors exist independently of my own perceptions. But this is problematic.
Why should the colors that constitute the world around me be any less subjective than the colors that constitute my phosphene experiences or the colors that constitute my imaginary/memory images? Are the colors that constitute my memories part of the world as well? Or are they private and subjective? How does one demarcate objective from subjective colors?
Observation 2: If I press on my eyelids while perceiving an object, the object suddenly splits in two -- the original object and a double image. The degree to which I press on the side of my eyelid can control the double image. The same effect can be caused by crossing my eyes. Now what exactly is the nature of this double image? It seems like the double image is just vibrations of colors in my visual field. So what about the colors in this double image of which I am aware? What is the external world response to this? Why isn't everything I see nothing more than a similar vibration of color?
If I keep press in my eyes again, upon opening them I can see "stars" fluttering around... Are these stars part of the objective world as well? Do they continue to exist when I am no longer perceiving them?
To be an external world realist would mean to affirm statements like, "The aisles at Walmart still exist when I'm not walking through them", "there is cereal inside of the boxes when I am walking through the cereal aisle". But I don't even know what it is that I am affirming. What does unseen cereal look like? What does an unseen aisle at the Walmart look like? What is the nature of its existence? Is it the SAME as when I am perceiving it? I have no knowledge of unseen cereal; I only have knowledge of seen cereal. So I really have no idea what it is that I affirming.
Sure I can say, "there is cereal inside these boxes". I can say it. But I really have no idea what it is I am affirming since I have no knowledge of unseen cereal.